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Physiological Achilles Tendon Length and Its Relation to Tibia Length

Rosso, Claudio MD, MSc*; Schuetz, Philipp MD, MPH; Polzer, Caroline MD*; Weisskopf, Lukas MD; Studler, Ulrich MD§; Valderrabano, Victor MD, PhD*

Clinical Journal of Sport Medicine: November 2012 - Volume 22 - Issue 6 - p 483–487
doi: 10.1097/JSM.0b013e3182639a3e
Original Research

Objective: The optimal intraoperative Achilles tendon length (ATL) adjustment is crucial for the physiological functioning of the musculotendinous unit. To date, the resting ATL and its relation to tibia length (TL) have never been defined in healthy subjects. We thus performed metric measurements of the ATL and TL.

Design: Case series.

Setting: Clinical and radiological measurements.

Participants: Fifty-two subjects placed in a 3-T magnetic resonance imaging with the ankle in neutral position.

Main Outcome Measures: Unilateral ATL measured from the calcaneal insertion to the beginning of the medial gastrocnemius muscle, TL measured from the intercondylar eminence to the center of the ankle, and qualitative tendon parameters in T2 sequences and human parameters were noted; results were correlated with age, gender, body height, weight, body mass index (BMI), and side of the AT and TL.

Results: The mean ATL was 180.6 ± 25.0 mm and the mean TL was 371.9 ± 25.4 mm with an ATL:TL ratio of 49 ± 5%. Achilles tendon length correlated significantly with body height (R2 = 38%, P < 0.0001) and with TL (R2 = 41%, P < 0.0001) but did not correlate with age, BMI, and side of the AT. Tibia length correlated with body height (R2 = 83%, P < 0.0001) and in multivariate linear regression, TL was the only independent predictor of ATL following the algorithm, ATL (mm) = 0.6 × TL (mm) − 53 (R2 = 41%).

Conclusions: We defined a new way to measure the ATL in a consistent way in healthy subjects and showed correlations between ATL, TL and body height and defined an algorithm of ATL based on TL. The ATL and the ATL-algorithm might be important in patients with impaired tendons such as AT ruptures.

*Orthopaedic Department, University Hospital Basel, University of Basel, Basel, Switzerland

Harvard School of Public Health, Boston, Massachusetts

Rennbahn Clinic, Muttenz, Switzerland

§Department of Radiology, University Hospital Basel, University of Basel, Basel, Switzerland.

Corresponding Author: Claudio Rosso, MD, MSc, Orthopaedic Department, University Hospital of Basel, University of Basel, Spitalstrasse 21, 4031 Basel, Switzerland (

Supported by a grant from the Swiss National Accident Insurance Company (SUVA). Each author certifies that he or she has no commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article. In addition, each author certifies that his or her institution has approved the human protocol for this investigation, that all investigations were conducted in conformity with ethical principles of research and that informed consent for participation in the study was obtained.

The authors report no conflicts of interest.

Received February 20, 2012

Accepted June 7, 2012

© 2012 Lippincott Williams & Wilkins, Inc.